The present invention is related to microphone devices. More particularly, the present invention provides a method and device using integrated MEMS and circuits for a microphone application. Merely by way of example, the microphone can be applied to cellular phones, blue tooth applications, hearing aids, records, camcorders, cameras, or any other application that includes voice.
Conventional Electret Condenser Microphones (ECM) have been widely used in mobile phones and audio equipment. ECMs, however, have major limitations particularly in mobile electronics. That is, ECMs have large form factors. ECMs are also costly and difficult to manufacture efficiently. Besides the large size and high operating voltages, ECMs often cannot sustain typical surface mount temperature of ˜260 Celsius. Accordingly, ECMs are often hand soldered, which leads to significant manufacturing costs and inefficiencies.
To overcome limitations of ECMs, silicon microphones have been proposed. Silicon microphones have advantages over conventional ECMs. That is, silicon microphones are generally fabricated in a similar ways to integrated circuits to significantly reduce its size and resulting form factor. It is also surface mountable using conventional pick and place methods for board level assembly. It has superior temperature and humidity performance, and lower power and potentially lower cost comparing to ECMs. Although silicon microphones have been successful, limitations still exist. The incumbent silicon microphone technologies are based on MEMS fabrication processes such as bulk and surface micromachining techniques. Accordingly, silicon microphones are still difficult to manufacture efficiently.
Thus, it is desirable to improve silicon microphones.